The present invention is directed to a medical device for the insertion of intravenous catheters. More specifically, the present invention relates to a catheter insertion device having a retractable needle and to manufacturing methods for the same.
When a catheter is inserted into a patient for the intravenous delivery of a fluid, a disposable needle passing through the catheter cannula is utilized to make a puncture to permit entry of the tip of the cannula into the patient. The needle is then withdrawn leaving the catheter in place either for a connection to the tube of a fluid delivery system. The catheter may also be capped at that time of insertion for later use. The needle used for inserting the cannula no longer has any utility and may now be contaminated with blood or other body fluid that poses an infection or other risk to medical practitioners. Accordingly, the needle must be disposed of without creating a risk of needle sticks to the medical practitioners inserting a catheter. A danger to clean up and medical waste disposal personnel continues if the used needles are not rendered harmless in some way. Caps or covers that can be mounted over the needle are not a satisfactory solution because they must be put in place and can come loose and expose the used needle. A discussion of the dangers associated with various approaches and uses of cannula insertion products is found in U.S. Pat. No. 4,747,831 to Kullie, which is incorporated herein by reference.
Retractable needle mechanisms have been recognized as a solution to some of the safety and disposal problems created by catheter needles. In such retractable needle mechanisms, a cannula insertion needle projects from the forward end of the catheter mechanism. The mechanism includes a handle that the medical practitioner grasps while inserting the catheter. The handle includes a hollow portion or sleeve of sufficient size to enclose the needle. After use, to start a cannula, the needle is released from the end of the handle and its sharp end retracted into the handle, beyond reach. Preferably, the handle has an aperture big enough for the needle, but too small for fingertips. The needle rides in a needle support that slides within the handle. Initially, the needle support is secured in the handle against the forward end, with the sharp end of the needle protruding outward through the aperture. After the cannula is in place, a release mechanism is triggered. Once the release mechanism is triggered, a coiled spring drives the needle support rearward to retract the needle into the sleeve of the handle. At the rear end of the handle a stop halts the needle support and needle so that they are safely confined within the handle.
The prior art recognizes two general categories of mechanisms for triggering retraction of the catheter needle. In a first category, a manually releasable latch holds the needle support, and thus the needle, in the extended position. After the cannula is in place, the medical practitioner manually triggers the needle support latch by affirmatively actuating a release trigger. This actuation may include squeezing or rotating stop elements out of engagement with the needle support. For example, U.S. Pat. No. 4,747,831, identified above, discloses a manually triggered retraction mechanism.
The prior art also recognizes a second category of triggering mechanism. In the second category, the mechanism is triggered automatically when the medical practitioner withdraws the needle from the cannula after the cannula has been inserted into the patient. In some examples, the needle support is held in place by a latch mechanism that is biased in place by the cannula hub. As the handle is removed from the cannula hub, the latch mechanism actuates, and the needle is automatically retracted into the handle. U.S. Pat. No. 5,562,634 to Flumene, et. al., which is incorporated herein by reference, discloses an automatically retracting needle.
Both of the manually activated and automatically retracting mechanisms provide advantages and disadvantages. For example, the manually activated retraction mechanism provides the medical practitioner with more control of retraction, allowing for more control over use and positioning of the catheter. Conversely, this mechanism has the disadvantage of requiring a separate action to retract the needle, which may be difficult or potentially dangerous depending on the situation. In contrast, while automatic retraction mechanisms have an advantage of not requiring an additional retraction step, catheter disassembly from the retraction device is not fully under the timing and control of the medical practitioner because retraction results in immediate separation of the device from the cannula assembly.
Depending on the particular situation in which the catheter is being used, or the preferences of medical practitioner, one or the other retraction mechanism may be preferred. However, prior designs of the different retraction systems have differed notably, having significantly different overall designs and components. This approach has required greater design and development work, practitioner training, and, in particular, greater manufacturing time and materials.
Accordingly, a need exists for a retractable needle intravenous catheter that is more readily adaptable to being manufactured and used with either an automatic or manually retracting needle mechanism.
While the invention is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.